iTunes does not recognize my AppleID

I am able to log into icloud from any browser, access the App store etc., however when trying to log into itunes I get an endless error that it doesn't recognize my Apple ID or password. It is so frustrating because I am trying to reset my ipad.

I get the same error when restarting my computer. A popup asks me to enter my Apple ID password yet won't accept it. I get an endless loop unless I hit cancel.